If 6xy = x2y + 9y, what is the value of xy? (1) x = 2 (2) x : DS Archive
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 18 Jan 2017, 21:31

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# If 6xy = x2y + 9y, what is the value of xy? (1) x = 2 (2) x

Author Message
SVP
Joined: 28 Dec 2005
Posts: 1575
Followers: 3

Kudos [?]: 147 [0], given: 2

If 6xy = x2y + 9y, what is the value of xy? (1) x = 2 (2) x [#permalink]

### Show Tags

05 Jan 2009, 18:26
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions

### HideShow timer Statistics

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

If 6xy = x2y + 9y, what is the value of xy?

(1) x = –2

(2) x = 3
SVP
Joined: 07 Nov 2007
Posts: 1820
Location: New York
Followers: 34

Kudos [?]: 862 [0], given: 5

### Show Tags

05 Jan 2009, 21:47
pmenon wrote:
If 6xy = x2y + 9y, what is the value of xy?

(1) x = –2

(2) x = 3

In the above quesion I am assuming x2y = x^2*y

(1)
x=-2
-12y = 9y+9y --->30y=0
->y=0
xy=0
suffcient
(2)
x=3

18y=9y+9y --> 18y=18y
---> we don't get single solution from this equation
Y can be any thing
not sufficient

_________________

Smiling wins more friends than frowning

Manager
Joined: 15 Apr 2008
Posts: 165
Followers: 2

Kudos [?]: 12 [0], given: 1

### Show Tags

06 Jan 2009, 12:17
x2suresh wrote:
pmenon wrote:
If 6xy = x2y + 9y, what is the value of xy?

(1) x = –2

(2) x = 3

In the above quesion I am assuming x2y = x^2*y

(1)
x=-2
-12y = 9y+9y --->30y=0
->y=0
xy=0
suffcient
(2)
x=3

18y=9y+9y --> 18y=18y
---> we don't get single solution from this equation
Y can be any thing
not sufficient

how did you get 9y for X^2y. shouldn't it be 4y
Manager
Joined: 04 Jan 2009
Posts: 241
Followers: 1

Kudos [?]: 12 [0], given: 0

### Show Tags

06 Jan 2009, 13:39
is there a typo in the original equation?
6xy = x2y+9y
If we treat x2y = 2xy;
4xy=9y=>y=0 or x=9/4.
So problem is solved from question stem itself.
Now if x2y = X^2*y; here is the soltuion:
6xy = x^2*y+9y=(x^2+9)*y
y=0 or
x^2-6x+9=0;
(x-3)^2 = 0 and hence x=3.
If x=3, we still need another equation to solve for y. So, (2) is not enough.
If x=-2,
-12y = 4y+9y=>-12=13 if y=!0. Thus, y=0 and xy can be determined. Hence, (1) is enough.

SVP
Joined: 07 Nov 2007
Posts: 1820
Location: New York
Followers: 34

Kudos [?]: 862 [0], given: 5

### Show Tags

06 Jan 2009, 14:08
ALD wrote:
x2suresh wrote:
pmenon wrote:
If 6xy = x2y + 9y, what is the value of xy?

(1) x = –2

(2) x = 3

In the above quesion I am assuming x2y = x^2*y

(1)
x=-2
-12y = 9y+9y --->30y=0
->y=0
xy=0
suffcient
(2)
x=3

18y=9y+9y --> 18y=18y
---> we don't get single solution from this equation
Y can be any thing
not sufficient

how did you get 9y for X^2y. shouldn't it be 4y

you are right.. it should be 4y .. type mistake..

_________________

Smiling wins more friends than frowning

SVP
Joined: 28 Dec 2005
Posts: 1575
Followers: 3

Kudos [?]: 147 [0], given: 2

### Show Tags

06 Jan 2009, 15:11
my bad guys, x2y = x^2y.

And yes, A is the correct answer
Intern
Joined: 25 Nov 2008
Posts: 9
Followers: 0

Kudos [?]: 0 [0], given: 0

### Show Tags

07 Jan 2009, 06:17
The equation: 6xy=x2y+9y
equivalent to y(x-3)^2=0
means: x=3 or y=0
A, x=-2 => y=0
B/ x=3=> insulf to determine y

hence A is the best answer
Re: DS: Equations 2   [#permalink] 07 Jan 2009, 06:17
Display posts from previous: Sort by